Recently, as interest in energy conservation and environmental issues is rising, the decrease of a fuel consumption ratio of cars is required. As one method for realizing the requirement, a method for decreasing exothermic properties in tires using an inorganic filler such as silica and carbon black in a rubber composition for forming tires has been suggested. However, the dispersion of the inorganic filler in the rubber composition is not easy, and the physical properties of the rubber composition such as abrasion resistance, cracking resistance and processability are rather degraded.
To solve such limitations and to increase the dispersibility of an inorganic filler such as silica and carbon black in a rubber composition, a method for modifying a polymerization active part of a conjugated diene-based polymer obtained by anionoic polymerization using an organic lithium, using a functional group which may interact with an inorganic filler has been developed. Particularly, a method of modifying a polymerization active terminal of a conjugated diene-based polymer into a tin-based compound or introducing an amino group into thereof, a method of modifying thereof into an alkoxysilane derivative, or the like has been suggested. However, when preparing a rubber composition using the modified and conjugated diene-based polymer which is modified by the above-described method, low exothermic properties may be secured, but the improving effects of physical properties of the rubber composition such as abrasion resistance, processability, or the like are insufficient.